Is a part-time diet better?

Losing weight is crucial for good health and reducing our risk for disease — but we know it’s easier said than done! In the fight to find a diet plan people will actually stick to, experts have found a new weapon: an “intermittent” diet. Rather than cutting calories every day, you might lose more weight if you’re strict just two days a week — even more when you cut the carbs.

Sounds too good to be true? Here’s the skinny on the latest study presented at the San Antonio Breast Cancer Symposium this past December. Researchers at the Genesis Prevention Center at the University of Manchester Hospital in England set out to find a realistic way to help people lose weight and thereby reduce their risk for cancer. Previous research showed that women can decrease their risk for breast cancer by up to 40 per cent simply by losing weight. The trick is finding a realistic plan to follow.

“Weight loss and reduced insulin levels are required for breast-cancer prevention, but [these levels] are difficult to achieve and maintain with conventional dietary approaches,” said the study’s lead author and dietitian Michelle Harvie, in a statement.

In this study, all 115 participants were women who are at a high risk of breast cancer thanks to family history. Participants were randomly assigned to one of three groups:

– The first group ate their “normal” diet five days a week and ate a carbohydrate-free diet of 650 calories two days a week. For those two days, foods like pasta, rice, breads and starchy vegetables were off the menu.

– The second group followed a similar diet to the first, except participants didn’t have to count calories on the two carb-free days. Essentially, they could have all the healthy fats, proteins and vegetables they wanted.

– The third group followed a 1500 calories/day Mediterranean style diet — a typical weight loss approach.

The results? After four months, both “intermittent” diet groups lost more weight than the third group who followed a calorie restricted diet. Members of the first group lost an average of 4 kg (about 9 lb) compared to the third group’s average of 2.4 kg (about 5 lb).

However, weight loss wasn’t the only benefit: other health markers like insulin and leptin were affected too. The first group saw their insulin resistance drop by 22 per cent and the second group by 14 per cent — but the third group only saw a decrease of 4 per cent. (Another important finding as insulin resistance contributes to type 2 diabetes.)

In short, cutting calories is good — but cutting carbohydrates may be better. Best of all, you don’t have to do it every day. Researchers are hopeful that an intermittent diet plan may provide a realistic alternative for overweight people looking to lose weight.

Are the results surprising? Previous research conducted by Harvie and colleagues found that intermittent diets offered the same benefits as consistently cutting calories — at least in pre-menopausal women. In a previous study, women who ate a restricted diet of 650 calories two days a week lost as much weight and showed the same improvement in other health markers as women who followed the 1500 calorie day diet. Those two days at 650 were also carbohydrate-free — and yes, recipes and meal ideas were provided. (Read the study abstract and press release for more information.)

Will it work for you?

While some reports say you can try this idea at home, you might be wise to be skeptical. Those five days aren’t dietary free-for-alls. For many people, simply following a healthy diet every day is challenging enough without adding two days of further sacrifice.

Researchers also caution that more investigation is needed. The results haven’t been published in a peer reviewed journal yet, and aren’t currently posted on the centre’s website.  And there’s still some room for critique. For instance, when it comes to any weight loss study, critics often point out that participants often have characteristics the general public doesn’t — often they’re obese or significantly overweight but otherwise healthy. If you aren’t in the same weight range or you have an underlying health condition, you may not see the same results. Sex, physical activity and age could all play a role in the amount of weight loss.

While these findings seem in line with other studies and popular diet plans that praise substituting carbohydrates with protein, critics also point out that there hasn’t yet been any study into the long-term effects of high protein diets. Even in the short term, some people experience side effects like constipation, higher blood pressure and stress on the kidneys. Attempting these diets can also be a painful experience for people with gout as a high protein diet can also be high in purine. Limiting carbohydrates intermittently could be a help to some or a problem for others — we don’t know that yet.

So what’s the bottom line? This variation of the intermittent diet shows promise in the “battle of the bulge” and could be an important trend to watch. The study’s authors say these findings should prompt more research into the link between carbohydrate consumption and breast cancer.

However, experts still recommend people talk to their doctors before making changes to their diets — especially if they have underlying health conditions like diabetes. Diets have their benefits, but they can also have disadvantages too.

For more information about the study, see the article on Time HealthLand.

Additional sources: Arthritis,, WebMD

Photo © winterling

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